It is necessary to evaluate the performance of respiratory apparatus with associated control and regulating loops during the development: and use of these apparatus. Furthermore, it is desirable to practice the manipulation of such apparatus and to learn the consequences of their use before they are placed into service for their intended use. For both purposes, it is desirable to avoid investigations on test persons and animals. Simulators of various kinds are described which permit the mechanical as well as the physiological functions to be simulated and demonstrated which occur during ventilation. One such simulator is disclosed in the published German Patent Application DE-OS No. 30 49 583.
The method necessary to operate the known simulator provides that a respiratory apparatus in the form of a pneumatic drive unit is provided with a breathing gas of varying composition which thereafter is conducted via a breathing circuit to an arrangement simulating the lungs. The lungs themselves are formed by means of displaceable rubber bellows which can expand against a resilient force when they are pumped full with breathing gas. In this way, the functions of the lungs such as compliance (C) or resistance (R) are imitated. Since carbon dioxide is formed in the human body during breathing, such an enrichment of carbon dioxide can be achieved by metering the carbon dioxide into the breathing circuit.
Further physiological functions such as oxygen consumption during ventilation, however, cannot be simulated. Since ventilation also must be conducted during anesthesia, the physiological effects of anesthetic gases must also be considered. No possibility of a simulation for this purpose is provided in the known arrangement.